nemudd,
You start with the sizing die, if it has the tapered decapping rod ( depriming rod ). Most 7mm TCU die sets ( 2 die sets ) have the tapered rod; but, not all. It is quite easy to disassemble the die and check the rod. The die manufacturer can provide a tapered rod, if your set does not have one. Additionally, you should lube the inside of the case necks prior to resizing. A Q-tip with Redding resizing lube / wax works great. Also, use new brass. Fired brass has been worked and you will lose more cases. Remember, when sizing, slow, steady pressure works best. When fireforming the cases reduce loads 10-15% from max. I've made many cases that was and lost very few in the process.